Cleveland Indians pitcher Paul Byrd stands during pre-game warmups before his team plays the Boston Red Sox in Game 7 of Major League Baseball's ALCS playoff series in Boston, Massachusetts October 21 2007. Byrd admitted to using human growth hormone prescribed by his doctors. REUTERS/Adam Hunger (UNITED STATES)

Photo: Adam Hunger, Reuters

Cleveland Indians pitcher Paul Byrd stands during pre-game warmups...

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Cleveland Indians pitcher Paul Byrd stands during pre-game warmups before his team plays the Boston Red Sox in Game 7 of Major League Baseball's ALCS playoff series in Boston, Massachusetts October 21 2007. Byrd admitted to using human growth hormone prescribed by his doctors. REUTERS/Adam Hunger (UNITED STATES) 0

Photo: ADAM HUNGER

Cleveland Indians pitcher Paul Byrd stands during pre-game warmups...

Image 3 of 3

Cleveland Indians pitcher Paul Byrd speaks to reporters outside the Indians clubhouse before Game 7 of the American League Championship baseball series against the Boston Red Sox Sunday, Oct. 21, 2007, at Fenway Park in Boston. Byrd responded to a published report he bought nearly $25,000 worth of human growth hormone and syringes from 2002 to 2005. (AP Photo/Charles Krupa) EFE OUT

Cleveland Indians pitcher Paul Byrd acknowledged Sunday that he had used human growth hormone purchased from a Florida anti-aging clinic that is the focus of law-enforcement scrutiny, saying he suffers from a rare condition that required him to use the powerful muscle-building substance.

"I have never taken any hormone or drug that was not prescribed to me by a doctor," Byrd told more than 100 reporters during a press conference at Boston's Fenway Park two hours before Game 7 of baseball's American League Championship Series. The Red Sox won the game 11-2, eliminating Cleveland from the playoffs.

The press conference, and two online interviews posted before the game, represented Byrd's response to a story in the Sunday Chronicle reporting that the 36-year-old pitcher had paid nearly $25,000 to the Palm Beach Rejuvenation Center for growth hormone between August 2002 and January 2005. For two days before the Chronicle story was published, Byrd had declined repeated interview requests.

In an interview with Foxsports.com on Sunday, Byrd was quoted saying that the Indians and Major League Baseball had been aware for some time that he had a "pituitary gland issue." However, both MLB and the Indians said they were not aware of Byrd's use of growth hormone until now.

MLB issued a statement saying it would investigate Byrd's use of the substance, and MLB had never given the pitcher clearance to use the drug, spokesman Patrick Courtney said.

Indians General Manager Paul Shapiro said he had been unaware of Byrd's use of growth hormone until Friday. That was the day The Chronicle called the club for comment on the matter.

Baseball officials planned to meet with Byrd to discuss his use of growth hormone.

In the press conference and in the online interviews, Byrd said he had been diagnosed with adult growth hormone deficiency and had been prescribed growth hormone to remedy the condition. He also said he had been diagnosed this spring with a tumor on his pituitary gland. He did not elaborate on who made the hormone deficiency diagnosis or when it was made, nor did he offer explanations about specific aspects of his interactions with the wellness center, including why some of his prescriptions were written by a dentist.

Byrd told Foxsports.com he no longer uses growth hormone, but asked at the press conference if he was still taking the drug, the pitcher said, "That's a private matter right now with me. I do still have a pituitary issue."

Baseball banned growth hormone in January 2005, about two weeks after Byrd's last shipment of growth hormone from the rejuvenation center.

The Palm Beach Rejuvenation Center is part of a national network of clinics and online pharmacies targeted by the district attorney of Albany, N.Y., for alleged illegal drug sales and prescription fraud. An executive and a physician associated with the rejuvenation center are among 10 people who have pleaded guilty to felony charges in the case.

According to a law enforcement source with knowledge of the investigation and the wellness center's business records, two of the 13 growth hormone prescriptions that Byrd obtained from the center were not written by a physician, but were signed by a Florida dentist who later had his license suspended for fraud and incompetence.

Law enforcement authorities in Florida are scrutinizing prescriptions written by the dentist and the two doctors who also signed Byrd's prescriptions, said the source, who asked not to be quoted by name because he was not authorized to comment on the matter.

Investigators have found no evidence that either the dentist or the other two physicians had ever ordered tests related to pituitary issues or growth hormone deficiencies for any of the patients for whom they had prescribed growth hormone, the source said. Also, one of the company executives who pleaded guilty in the case, Joseph Raich, told investigators that none of the three doctors performed those tests on patients, the source said.

Byrd denied any knowledge of problems related to the wellness clinic or the pharmacies that sent him the drugs.

"If that pharmacy did something wrong, I did not know about it, and I never received anything in a shipment that wasn't prescribed to me," he said. "I have never received anything in the mail that wasn't prescribed to me by a doctor."

Byrd, a 12-year veteran, said he had never tried to hide his use.

"I purchased things with my credit card, on my name, things came to clubhouses of teams that I played on," he said. "I've taken blood tests set up by a team in different towns. Everything has been done out in the open. I have actually had shipments come to clubhouses and have actually for a small period of time stored them in the refrigerator in the clubhouses."

Byrd, who lives near Atlanta in the off-season, told ESPN The Magazine that he had been referred to the Florida center by a physician in Marietta, Ga. He had never been examined by any of the doctors at the Florida centers, ESPN quoted him as saying. Instead, he said he had blood tests and telephone consultations every three months.

According to medical journals, adult-onset growth hormone deficiency is a rare condition often caused by a tumor on the pituitary gland, the body's natural source of growth hormone. The ailment causes depression, anxiety and weight gain, according to a 2000 article in the Pharmaceutical Journal. It is treated with a prescription for synthetic growth hormone.

Few physicians encounter the ailment.

The emedicine.com Web site estimates that only 35,000 adults in the United States - about one in every 8,500 people - suffer from adult-onset growth hormone deficiency. Diagnoses are tricky, according to the Pituitary Network Association medical Web site. The association says tests for pituitary problems should be performed at a hospital with a special neuroendocrine testing unit. Treatment is best left to an endocrinologist who specializes in pituitary disease. Byrd is the second major league player to announce he has the condition.

In 2006, after federal agents seized a package of growth hormone from then-Arizona Diamondback pitcher Jason Grimsley, Grimsley provided investigators with the names of several big leaguers who he said also used the drug, court records show. The government never made the names public. But former major league infielder David Segui told ESPN he was on Grimsley's list, saying he had obtained the drug through a "wellness clinic" in Florida.

"I was, you know, deemed human growth hormone deficient through blood work," Segui told ESPN at the time. "The doctor put me on human growth hormone, monitored my levels. ... It was perfectly legal. You know, I was under a doctor's care."

In an unpublished book, Byrd wrote that he had considered using large doses of growth hormone in hopes of improving his athletic performance. But he said his devout Christian faith helped him resist the temptation, Fox Sports.com reported.

"I wondered if I doubled my prescribed dose, whether or not I would throw harder and have a better and possibly longer career. After all, I had a prescription," Byrd wrote according to the Fox Web site. "Then I prayed and realized that God was in control of my life, and he wouldn't want me making money through cheating the system."